Thread: vac leak, O2 code, exhaust leak.

Kind of a dead thread but im experiencing the same thing almost but im running on a stock pulley with sd headers and 3 in exhaust. Engine only has bout 2500 miles on it. i still need to put a new fuel filter on it but i dont know if that would help any. The car has just seemed kinda sluggish and my throttle response isnt the greatest. just doesnt seem like im making the power i should be but im not sure if im just expecting to much. I know i need a tune but just didnt know if anyone would have any suggestions on other things i should try? i do know i have a tiny exhaust leak to on my crossover for my headers but that should be getting fixed tomorrow

alright thanks guys. i have a HAI. i do have that small leak in the crossover on the headers but hopefully will be able to fix that tonight. i have a p0135 code come up twice so im gonna try changing the o2 sensor also. and then when comparing my vac to a couple of my buddies at work today im only pulling about half the vac they are. dont know if it matters that ones a turbo cobalt and the other is a supercharged civic si but i would think i should still be getting about the same vac as they do at an idle. they are getting 20 and im getting bout 9.5 or 10 so im pretty sure ive got a vac leak somewhere just need to find it. also on the to do list is the fuel filter that never got changed when the new engine got put in so i dont know if that f'ing anything up to.

I wouldn't compare any GP to a TC Cobalt or a Civic SI. Not the same car thus may be different readings.

I assume your car is a 2000 GTP. What other mods have you done besides the HAI, headers, leaky crossover?

When was the last time you put new plugs/wires on it? You running platinum plugs in it? Running 91+ octane?

I'd change the fuel filter, air filter, clean the MAF and fix the exhaust leak and replace the O2 and see what you get. Other than that take a look at the vacuum T under the snout. They like to crack. Then you can try spraying brake/carb cleaner around ALL your vacuum fittings and LIM/SC area to see if you can make the motor change tone/stumble, etc... If you find a place that the spray makes a difference then there is a vac leak there. Is your HVAC working properly?

thanks for the suggestions guys. i have a hai and i have not checked the motor mounts yet but have flipped the dogbones. still have the small leak on my crossover because i didnt have any time to fix it today with work and bball. did do a lil comparing with a couple buddies at work today and notice that they are both getting a lot more vacuum than i am. one is a turbo cobalt and the other is a supercharged civic si and they were both sitting at about 20 at an idle and im sitting at about 9 to 9.5 at an idle. I dont know what i should be getting but i would think it should be pretty close to what they are getting while im just sitting at an idle. today i did scan it and see that a p0135 code popped back up. this is the second time ive seen it so im thinking i might have a bad o2 (bank 1 sensor 1). also on the to do list is a new fuel filter that never got put in when the engine did. Another thing ive noticed is it smells pretty rich but i was just thinking that was because i no longer have a cat. Any way i know i should start checking for vac leaks maybe change the o2 sensor unless you guys think otherwise and get my exhaust leaks fixed. cleaning the throttle body and maf prolly isnt a bad idea either since i dont think that has ever been done and i think i could possibly have the couple on my sc going out. im starting to hear a lil rattle coming from the sc at idle, its not as bad as some of the vids ive seen on youtube but there is a slight rattle there so it prolly couldnt hurt to change the coupler. dont know how much all of this will help but i didnt just drop all this money so i couldnt go fast Again thank you guys for all the suggestions and keep em coming if you guys feel like im missing anything

You have your own thread.

Lol Matt... I'd say clear up the O2 sensor issue first and see what that gets you. Running rich is a good sign that the O2 is unhappy. Also, I'm not 100% sure but I thought when you eliminate the cat that you need a tune to do so. I could be wrong though.

Originally Posted by FordMan77

Is your HVAC working properly?

I do have ac and heat but bout a week after the new engine went in my blower motor stopped working.

Dead blower motor wouldn't cause a vac leak, just a hot interior, lol... Any luck w/ the O2 code?

lol yeah and today it was really hot... i cleared the code like 3 or 4 days ago and it hasnt come back but since i found that i have a vac leak i have been taking it easy on the car. I have a full vac line kit coming that should be here tomorrow or thursday and since none of my local autoshops have them im going to be ordering some stepped band clamps tonight too so i can fix my exhaust leak before the o2.

alright well i got the o2 code covered and just changed all my vac lines yesterday and i still have a vac leak somewhere. any other suggestions on the vac leak?

Start spraying carb cleaner around all the sealing surfaces (TB, S/C,etc) and all your new lines. One of them has got to be leaking still. Check the brake booster as well where the large line come from it. Sometimes the check valve can go bad in it.

Originally Posted by FordMan77

Start spraying carb cleaner around all the sealing surfaces (TB, S/C,etc) and all your new lines. One of them has got to be leaking still. Check the brake booster as well where the large line come from it. Sometimes the check valve can go bad in it.

i took brake cleaner and did this and couldnt get the motor to stumble or change tone anywhere and while i was replacing all of the vac lines i did check to make sure the check valve is working properly and it was. While i replacing the line that runs under the snout of the s/c i did notice that there was s/c oil on it so i dont know if i should pull everything off again and check the gaskets cuz im thinking the guy the did my new motor didnt put new gaskets on when he took the s/c off my old engine and put it on the new one. The only thing is, i dont see anything else leaking around the s/c besides the little amount of oil leaking from under the snout. The new lines did help though because i was only getting 8 or 9 in Hg for vac before the new lines and now im getting 10 to 12 and if i rev the engine while in park it actually gets more vac... pops up to 12 to 13 when i rev it now and before the new lines it would just drop down to 2 to 4. I dont know if it makes any difference in finding the problem but ive noticed that while im cruising down the road at 60 to 65 my vac is anywhere from 4 to 6 and then if i let off the gas completely it will pop back up to 13 to 14 while i just coast. i dont know if any of this even helps but i dont know to much about this and im just trying to toss things out there in the hopes the it will help someone diagnose what is wrong.